In recent years, treatment of a disease using an antibody has rapidly been adopted through the advance of biotechnology. Also in Japan, various antibody preparations such as Synagis, Remicade, Rituxan and Herceptin are provided in the medical field.
When an antibody is stored in a solution for a long time, the formation of a chemically degraded product, the formation of an -insoluble aggregate, the formation of a soluble association or the like occurs. Therefore, in order to provide a stable and safe antibody drug, there has been a demand for a method of suppressing the formation of such substances.
When an antibody is stored in a state of a solution for a long time, a chemical degradation reaction such as cleavage of a disulfide bond or a peptide bond of an antibody occurs. As a result, there is concern for a decrease in its activity, an unexpected side effect or the like due to the deterioration in the quality thereof.
Protein is insolubilzed through aggregation of molecules whose higher-order structure is disrupted with disrupted high-order structure due to shaking, heat stress, or the like. When such an insoluble aggregate is intravenously administered, a serious side effect such as anaphylactic shock is liable to occur (Japanese Published Unexamined Patent Application No. 502938/98).
As the method of suppressing the formation of an insoluble aggregate, a method of adding citric acid at 100 mmol/L or more or heparin at 0.5% to antibody solution in order to suppress the formation of an insoluble aggregate caused by heat stress in an aqueous solution of a recombinant human keratinocyte growth factor is known (Journal of Pharmaceutical Science, Vol. 83, No. 12, 1657-1661 (1994)). Further, as the method of suppressing the formation of an insoluble aggregate caused by heat stress in an aqueous solution of an antibody, a method using a glycine buffer or a histidine buffer (WO 02/13860), a method of adding polyvinylpyrorridone at 2% or more (Pharmaceutical Research Vol. 11, No. 5, 624-632, 1994), a method of adding a phosphate buffer, sodium chloride and maltose (Japanese Published Unexamined Patent Application No. 504499/91), and the like are known.
Although some proteins may not lead to insolubilization, they are known to form a soluble association comprising a small number of protein molecule such as a dimer or a trimer. For example, when the protein is an antibody, it is considered that a soluble dimer is easily formed (Biochemistry, Vol. 38, 13960-13967 (1999)). In addition, when a dimer of an antibody is administered into the human body, there is a risk of causing a side effect such as fever, nausea or hypotension (Japanese Published Unexamined Patent Application No. 502938/98).
As the method for suppressing the formation of a soluble association, a method of adding a nicotinic acid derivative or an a-amino acid having a lipophilic side chain as a stabilizing agent into a liquid immunoglobulin preparation is known (Japanese Published Unexamined Patent Application No. 502938/98).
As described above, there has been a demand for a method of providing a stable antibody preparation which achieves the stabilization of the antibody in a solution by overcoming plural factors of instability such as the formation of a chemically degraded product, the formation of an insoluble aggregate and the formation of a soluble association. However, such a method has not been known so far.